1. Field of the Invention
The present invention relates to a charging apparatus for charging a battery pack provided with a rechargeable battery, a battery pack, and a rechargeable battery charging method.
2. Description of the Related Art
It is advantageous that various portable electronic apparatuses, such as a portable telephone and a lap-top computer, could be used over an extended period of time even after being disconnected from commercial power lines. For this purpose, measures are have been taken for increasing the power storage capacity of an exchangeable battery pack used as the power source to drive an electronic apparatus, as well as for decreasing the power consumption of the electronic apparatus.
In portable telephones, in particular, the trend is toward greater power consumption as the portable telephone provides an increasing variety of functions and is used at an increasing frequency due to the increasing variety of services provided via the portable telephone. However, they are still required to be capable of operating over a longer period of time even in such a situation.
Thus, users carry replacement battery packs to enable operation over a long period of time. A charging apparatus having a plurality of charging slots may also be used to charge a plurality of battery packs.
Battery packs of the prior art are charged by, for example, combining constant current charging and constant voltage charging. That is, the battery pack is charged in constant current charging until the voltage thereof reaches a predetermined voltage level, following by constant voltage charging for a predetermined period of time. Current flowing in the charging apparatus during constant current charging is determined by an AC adapter being used.
However, even when the charging apparatus has two charging slots, in the case where only one charging circuit is provided, the time required to fully charge both battery packs becomes twice the time required for fully charging one battery pack. This situation is no different than a case of sequentially charging two battery packs one by one using a charging apparatus having a single charging slot.
In order to make it possible to charge two battery packs simultaneously and reduce the charging time at the same time, two charging circuits may be provided, but this makes the charging apparatus more expensive and increases the size thereof, thus creating a problem in manufacturing a compact charging apparatus.
The present invention has been proposed in view of the problems of the prior art described above, and an object thereof is to provide a charging apparatus that is capable of reducing the charging time when charging a plurality of battery packs and that can also be made smaller in size. Also provided is a battery pack and a battery charging method.
In order to achieve the object described above, the charging apparatus of the present invention comprises a plurality of battery insertion sections into which a plurality of battery packs having a charge control capability and/or an electronic apparatus incorporating the battery pack are inserted, and a power source for supplying charge current, wherein the charge current from the power source is supplied to the battery packs and/or the electronic apparatus inserted into the battery insertion sections in parallel.
The charge control function refers to a function to start the charging operation, when the output voltage of the power source exceeds a predetermined threshold.
The charging apparatus described above applies the output voltage of the power source to the battery insertion sections in parallel.
In order to achieve the object described above, the battery pack of the present invention comprises a rechargeable battery wherein charging and discharging occur and a charge control section for sensing the output voltage of a charge power source to control the start and stop of charging, wherein the battery pack is connected in parallel with another battery pack or packs to the charge power source, and the charge control section senses a change in the output voltage due to charging of the other battery packs to control the start and stop of the charging operation.
The charge control section may start the charging operation when the output voltage exceeds a predetermined threshold.
The battery pack described above is connected in parallel with the other battery pack to the charge power source, and the charge control section senses a change in the output voltage of the charge power source due to charging of the other battery pack to control the start and stop of the charging operation.
In order to achieve the object described above, the rechargeable battery charging method of the present invention for charging a plurality of battery packs each provided with the secondary battery comprises a current supply step for sensing a charge current from the charge power source is supplied to the plurality of battery packs in parallel and a charge control process wherein a change in the output voltage of the charge power source due to charging of at least one battery pack among the plurality of battery packs to control the start and stop of charging the other battery pack.
In the charge control step, the charging operation may be started when the output voltage exceeds a predetermined threshold.
In the charge control step, the charging operation may also be switched between constant current charging and constant voltage charging according to the voltage level of the plurality of battery packs.
Further, the plurality of battery packs are charged individually in the constant current charging operation and the plurality of battery packs are charged simultaneously in the constant voltage charging operation, while the constant voltage charging operation for all battery packs is started when the voltages levels of all of the plurality of battery packs reach a predetermined voltage level.
According to the rechargeable battery charging method described above, in the charge control step, a change in the output voltage of the charge power source due to charging of at least one battery pack among the plurality of battery packs is sensed to control the start and stop of charging the other battery pack.
The charging apparatus of the present invention comprises a plurality of battery insertion sections into which a plurality of battery packs having the charge control function to control charging of the rechargeable battery and/or the electronic apparatus incorporating the battery pack are inserted, and a power source for supplying charge current, wherein the charge current from the power source is supplied to the battery packs and/or the electronic apparatus inserted into the battery insertion sections in parallel.
The charge control function may be a function to start the charging operation when the output voltage of the power source exceeds a predetermined threshold.
As a consequence, the charging apparatus described above can not only be made smaller in size due to the simpler construction thereof but can also to reduce the manufacturing cost. The charging apparatus is also capable of charging a plurality of battery packs simultaneously with a constant voltage. Thus it is possible to reduce the charging time when charging a plurality of battery packs without installing an additional charging circuit.
The battery pack of the present invention comprises a rechargeable battery wherein charging and discharging occur and a charge control section for sensing the output voltage of the charge power source to control the start and stop of charging, wherein the battery pack is connected in parallel with another battery pack to the charge power source, and the charge control section senses a change in the output voltage due to charging of the other battery pack to control the start and stop of the charging operation.
The charge control section may start the charging operation when the output voltage exceeds a predetermined threshold.
Therefore, the battery pack described above makes it possible to reduce the charging time.
The rechargeable battery charging method of the present invention for charging a plurality of battery packs each provided with a rechargeable battery comprises a current supply step for supplying a charge current from a charge power source to the plurality of battery packs in parallel and a charge control step for sensing a change in the output voltage of the charge power source due to charging of at least one battery pack among the plurality of battery packs to control the start and stop of charging the other battery pack.
In the charge control step, the charging operation may be started when the output voltage exceeds a predetermined threshold.
In the charge control step, the charging operation is switched between constant current charging and constant voltage charging according to the voltage level of the plurality of battery packs.
Further, the plurality of battery packs are charged individually in the constant current charging operation and the plurality of battery packs are charged simultaneously in the constant voltage charging operation, while the constant voltage charging operation for all the battery packs is started when the voltage levels of all of the plurality of battery packs reach a predetermined voltage level.
Thus the rechargeable battery charging method described above allows not only making the charging apparatus smaller in size due to the simpler construction thereof but also reducing the manufacturing cost. The rechargeable battery charging method is also capable of charging a plurality of battery packs simultaneously with a constant voltage. Thus, it is possible to reduce the charging time when charging a plurality of battery packs without installing an additional charging circuit to the charging apparatus.